Pitching in (PS45000 )

Subject: Pitching in
From:    PS45000  <PS45(at)MUSICA.MCGILL.CA>
Date:    Tue, 28 Sep 1993 18:28:23 EDT

Dear Ralf, Richard and other Pitchers The "tutorial on pitch" has some missing fundamentals: > A little tutorial on pitch... > "Frequency = pitch" is a convenient way of measuring or marking > pitch: The pitch of a sound may be measured by the frequency of a > pure tone whose pitch is judged to be the same as the pitch of that > sound (e.g., Fletcher, 1934; Plomp, 1967, 1976; Terhardt, 1972, > 1974; Terhardt et al, 1982). But neither the frequency scale nor its > logarithm is generally proportional to perceived pitch. > ........ etc. Yes. And to further reiterate the distinction between physical and psychological concepts: Pitch is a percept that for pure tones is closely related to physical frequency (but not 1:1). Sounds perceived to be of the same pitch may have different physical frequencies. 'Tis the job of us psychoacousticians to go a hunting for the physical correlates of auditory percepts and vice versa. > ............Richard's tutorial continued ......... > The mel scale and its relatives listed above apply only to pure > tones, and not (or at least not directly) to music or speech. For > complex tones, it is generally safe to assume that pitch is > proportional to the logarithm of frequency. This is true over a wider > range of frequencies for complex tones than for pure tones. To use the most popular sentence in human (mis)communication today: Whatcha talkin' 'bout Richard ???? Complex tones comprise many frequency components. Depending on the relationship between the components, a single unified pitch or multiple candidate pitches may be evoked. For a harmonic complex, that is composed of components that are all multiples of a common fundamental frequency, that fundamental frequency would likely be the strongest candidate for a pitch match (as achieved by the ASA 1960 criterion). This may be achieved even when the fundamental is not physically present in the spectrum (= Missing F0 or residue or virtual pitch). In any case, harmonics are not equally spaced on a log-frequency scale so I'm not sure which logarithm of which frequency is being referred to.in the "tutorial". The famous Green "profile" stimuli that comprise components that are equi-log spaced sound far from tonal and are more likely to be perceived as a collection of multiple, fuzzy pitches (like someone sitting on a piano keyboard) than a sound with a unified pitch sensation. Pitch is probably the most studied auditory attribute (at least with the longest history of research). Given some identifiable, straightforward physical and physiological substrates, it is relatively easy to evoke changes in and to measure (via generally relativistic or ordinal response criteria). Despite this long history of investigation, however, all the issues are not resolved (no pun intended). Pitch judgments are highly context sensitive. Depending on low-level sensory factors such as the "place" on the basilar membrane activated by a preceding or succeeding sound, the sound being judged may evoke different pitch judgments. E.g. residue sounds that differ greatly in spectral locus, may evoke ordinal pitch judgments despite equality of F0. "Higher level", cognitive factors may also affect pitch judgments. Different degrees of physical "mistuning" may be acceptable for a sound depending on musical constructs such as tonality and how well the mistuned sound can still "fit" into the scalar framework. I certainly don't mean to dishearten or discourage Ralf or any other potential pitchers out there from seeking the fundamentals about pitch perception. Just wanted to share my awe, enthusiasm and some knowledge about a sensational, if complex perceptual feature of sound. Since ear-ly Punita Singh

This message came from the mail archive
maintained by:
DAn Ellis <dpwe@ee.columbia.edu>
Electrical Engineering Dept., Columbia University